# Common issues & Fixes

# Errors "Failed to login - null" or "Failed to login - invalid session" when joining a server

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#### **Issue description**

These errors mostly happen when there is a Microsoft account autentication issue on your Launcher, whether it is Technic or CurseForge.

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#### **Solution**

Closing the game and launcher completely, logging out from the launcher and relogging back would be the most common fixes, but if that still doesn't work, you can access '%appdata%/roaming/.technic' and delete the 'oauth' folder.

If this still doesn't solve it, you can open a support ticket on our Discord server.